This gene is a member of a gene family which encodes enzymes responsible for the conversion of arginine residues to citrulline residues. This gene may play a role in granulocyte and macrophage development leading to inflammation and immune response. PADI4 plays a role in the epigenetics, the deimination of arginines on histones 3 and 4 can act antagonistically to arginine methylation. The protein may be found in oligomers and binds 5 calcium ions per subunit. It catalyses the reaction: Protein L-arginine + H2O = protein L-citrulline + NH3.